Magnetic chuck



May 12, 1925.

O. S. WALKER ET AL MAGNETIC cnucx Filed March 31, 1919 2 SheecsSheet 1 F 1 g. 1.

n l W/ May 12, 1925. 1,537,633

I o. s. WALKER ET AL MAGNETIC CHUCK Filed March 31, 1919 2 Sheets-Sheet 2 1 7 -Q 5 1 I 4 E *5 ii g l l 112 1 11 1 1 J 1 1 j 2b \1 8 6 9 /7 Q I T. g 7 12% 4? Patented May 12, 1925.

UNITED STATES PORATION OF MASSACHUSETTS.

PATENT OFFEQE.

3, 033 VIORCESTER, MASSACHU- CESTEE, lMASSACI-IUSETTS, A COR- MAGNETIC CEiUuK.

Application filed March 31, 191.9. Serial N0. 286,422.

To aZZ whom it may conocrn' Be it known that we, OAKLEY S. WALKER and Isaac FOWLER \VILLIAMS, both citizens of the United States, residing at lVorcester, in the county of lVorcester and Commonwealth of Massachusetts, have invented a new and useful Improvement in a Magnetic Chuck, of which the following, together with the accompanying drawings, is a specitication.

The present invention relates to magnetic chucks, and in particular to the construc tion and arrangement of the parts of a chuck of this class in such a manner as to preclude the access of water and moisture to the magnetizing coils thereof. The in vention is illustrated in its application t) a well known form of chuck having a removable face plate, with the pole pieces of the latter adapted to be energized by contact with a plurality of underlying cores contained within the shell or casing of the chuck. The invention contemplates Ills provision in various forms of a shield or other protecting element which is so disposed as to effectually protect the coils of the chuck from moisture, water, or other disintegrating elements that inevitably find their way into the interior of the magnetic chuck when the same is in use. The lllVGl'ltion is fully set forth in the following description, reference being had to the accent panying drawings, wherein Figure 1 is a plan view of a chuck embodying the invention.

Figure 2 is a longitudinal, sectional view of the chuck illustrated in 1, showing one form of shield or protecting device.

Figure 3 is a transverse sectional view of such a chuck, showing the same shield or protecting device.

Figure 4 is a transverse sectional view, similar to Fig. 3, showing a modified form of shield or protecting device.

Like reference characters refer to like parts in the different figures.

The type of chuck herein shown comprises a casing or shell 1 providing an interior space for the magnetizing devices which impart their magnetism to the pole pieces of the chuck face. As herein shown, these magnetizing devices take the form of one or more core castings 2, each of which provides plurality of spaced transverse projections or cores 3, 3. The core castings 2 are adjustably supported from the bot tom of shell 1 by means of a plurality of screws l, preferably of brass or other nonmagnetic material, which screws are accessible from the bottom of shell 1 to raise the cores 3, 3, into magnetic contact with the pole pieces of the chuck face.

Suitable windings or coils of wire 5, are disposed upon the several cores 3, 3, in such a manner as to impart opposite magnetic polarity to adjacent cores; that is, as shown in Fig. 2 every alternate core 3 will be magnetized to a positive polarity, while the remainder of said cores will be magnetized to a negative polarity. Each core 5 is adapted to impart its magnetism to one of the pole pieces 6 of the removable face plate of the chuck, said pole pieces. as herein shown extending transversely of said face plate, and being separated from the frame 7 thereof, and from each other by the usual gaps 8, 8, of nonmagnetic material, as is common in devices of tl class. In actual use, and especiall i in grinding operations where water is employed, the coils of a magnetic chuck are subjected to deterioration and short circuiting owing to the fact that water seeps into the interior through the joints between the pole pieces, and through the joints between the face plate and hell.

It is the purpose of the present invention to wholly segregate the coils 5, 5, from any such damaging action, and to this end it is proposed to provide a shield or protecting device for each of the multiple core castings 2, 2, which readily lend themselves to the use ofsuch a construction because of the fact that they are supported above the bot tom of the shell, and because of the fact that a plurality of coils 5, 5, are carried by each. One form of shield that is contemplated by the invention is shown in Figs. 2 and 3 comprising a one piece inverted hollow member 9 made of a thin sheet of tin or other suitable material, -which completely surrounds the core casting and its coils 5, 5, on the top and sides thereof. As shown in Figs. 2 and 3 the inclosure of the coils 5, 5,

and their core casting 2 is completed by a thin sheet of suitable material 10, which is soldered or otherwise integrally secured to chamber, and thus all possibility for deterioration or short circuiting is eliminated. The connections to the coils may be made in any well known manner through the walls of the vacuum chamber or through the stuffing box 11, as desired.

The face plate of the chuck is secured to the shell 1 by means of bolts 12, after which pressure is applied to the screws a, 4, to elevate the core casting 2 and its surrounding shield into contact with the pole pieces 5, 6, the screws 4:, 4t, bearing against the plate 10. It will be understood, of course, that the material of the member which is interposed between each core 8, 3, and its respective pole pieces 6, 6, is of suliicient thinness so as not to impede to any appreciable extent the magnetic flux.

In lieu of the disposal of the coils 5, 5, in a vacuum chamber, as above described, the construction of Fig. 4: may, under most conditions of operation, be employed. In this case the multiple core casting 2 with its coils 5, 5, is inclosed only on the top and sides by a shield 13 of thin waterproof material. The latter extends well below the bottom of the coils, and hence there can be no access of water to said coils unless said water rises to a considerable height in the interior of the shell. This is prevented by the provision of suitable drain holes in the bottom of the shell, as shown by the dotted lines in Figs. 3 and 4.

Vi e claim,

1. In a magnetic chuck, a shell having a detachable face plate, a multiple core casting supporting a plurality of coils above the bottom of said shell, and a thin shield of non-magnetic material surrounding said casting to prevent the access of moisture to said coils from the joint between said shell and said face plate, while permitting the passage of magnetic flux between said core and said face plate.

2. In a magnetic chuck, the combination with a shell having a face plate, of a multiple core casting within said shell, carrying a plurality of coils, a member of non-magnetic material covering and surrounding said casting to prevent the access of moisture to said coils, and adjustable means accessible from the exterior of said shell for elevating said casting and said member in unison, toward said face plate.

3. In a magnetic chuck, a shell having a detachable face plate, a core casting adapted to energize said face plate, a coil carried by said core casting and a thin shield of nonmagnetic material interposed between said face plate and said core casting and providing a depending wall surrounding said core casting and said coil, to prevent the access of moisture to said coil from the joint between said shell and said face plate. 7

i. In a magnetic chuck, a shell having a face plate, a vacuum chamber having walls of non-magnetic material disposed within said shell, magnetizing means for saidface plate completely inclosed in said vacuum chamber, and means for adjusting said magnetizing means toward and from said face plate.

5. In a magnetic chuck, a shell having a face plate, magnetizing means for said face plate within said shell, a vacuum chamber having walls of non-magnetic material inclosing said magnetizing means, and means operable from the exterior of the shell for moving said magnetizing means into operative relation to said face plate.

Dated March 20, 1919.

OAKLEY S. WALKER.

ISAAC FOIVLER WILLIAMS.

Witnesses Gino. IV. KENNEDY, J12,

PENELOPE CoMnEnnAci-i. 

